This invention relates to a device for preventing engine overrunning in a multi-cylinder internal combustion engine, and more particularly to an improved arrangement for inducing misfires in one or more cylinders of a multi-cylinder engine based on the detected speed of the engine.
Various devices have been proposed for preventing multi-cylinder engines from overrunning. In such devices, if the engine speed exceeds a pre-set limit, misfires are caused to occur in specific cylinders in order to lower the engine speed. With these devices, however, the ignition plugs of the cylinders tend to get wet with fuel since the misfires are always induced in the same specified cylinders. This can make it difficult to resume ignition in these cylinders after the engine speed has dropped, and can result in irregular running of the engine. In addition, with this type of arrangement the ignition plugs can become contaminated with carbon which can cause deterioration of the plugs and a shortened life span.
It is, therefore, a principal object of this invention to provide an improved overrun preventing device for a multi-cylinder internal combustion engine which causes misfires to occur in the cylinders in a random fashion or in a sequential order as often as is necessary, but which prevents the ignition plugs from getting wet with fuel so that later reignition can easily be attained if desired.
It is a further object of this invention to provide an improved overrun preventing device for a multi-cylinder engine which prevents the ignition plugs from being deteriorated by contaminating carbon.